Control means for hydraulic presses



Aug. 12, 1952 I R. COLLIER 2,606,610

CONTROL MEANS FOR HYDRAULIC PBESSES Filed March 21, 1950 3 Sheets-Sheet1 Aug. 12, 1952 R COL P 2,606,610

CONTROL MEANS FOR HYDRAULIC PRESSES Filed March 21, 1950 3 Sheets-Sheet2 //vz/E/v Toe E/CH/IRD COLL/5Q 57 mag Aug. 12, 1952 R. COLLIER2,606,610

CONTROL MEANS FOR HYDRAULIC PRESSES Filed, March 21, 1950 s Sheets-Sheeta Patented Aug. 12, 1952 CONTROL MEAN S FOR HYDRAULIC PRES-SE RichardCollier, Esher, England Application March 21, 1950, Serial No. 150,916In Great Britain August 25, 1949 6 Claims.

This invention relates to control means for hydraulic presses forproducing plastic mouldings from materials such as synthetic resins andparticularly those known by the registered trademark Bakelite.

During the cycle of a moulding operation it is usually necessary tocontrol the sequences of opening and closing of the dies with differenttiming to suit the nature of the moulding being produced. For example,with Bakelite, after an operator has charged adie with moulding powderand metal inserts, it is necessary to operate the press so that itcommences to close, then closes, and at a predetermined time afterclosing opens slightly momentarily to eiiect "breathing to allow theescape of gas to avoid blemishing the moulding. The dies are thenallowed to remain closed for a predetermined time to effect curing andare then opened and, when approaching the fully open position themovable die, which is usually the lower die, moves relatively to anejector pin device which acts to raise the moulding slightly from themovable die to enable an operatorto remove the moulding by means of ahand stripper. This means therefore that before the movable die canagain be charged with moulding powder, the die must again be movedslightly in relation to the ejector pin device to raise it clear of theejector pins and then retained in this charging position.

These operations with a'hydraulic moulding press have up to nowgenerally been efiected by an operator manually actuating two levers forcontrolling the inlet and exhaust of the hydraulic medium to and fromthe press and, in practice, an operator cannot handle more than twopresses at one time and keep them working constantly and efliciently.

It is the object of the present invention to provide a simple andreliable control mechanism which will enable all the operations (whichneed not necessarily be those referred to above) to be eiiectedautomatically in the correct sequence and with requisite timing betweenstages so that all an operator has to do is to charge a moulding pressand put the press into action, when the desired cycle of operations isefiected automatically. During this time the operator can attend toother presses. By fittin hydraulic moulding presses with the controlmeans of this invention it is estimated that'a single operator canattend to six presses and keep all of them constantly in action.

It has been found impracticable to secure efficiently the automaticoperation by simple continuously rotating cam mechanisms, operating theinlet and exhaust valves of the hydraulic press in predeterminedsequence and times, owing to variables which cannot conveniently beexcluded, such as variation in the pressure fluid supply to the presswhich causes fluctuations in the time occupied. in the closing andopening strokes This is very pronounced when a plurality of presses arefed from a main hydraulic system with the possibility of anindeterminate number of the presses working simultaneously or standingidle.

According to this invention, there is provided control means for ahydraulic press for producing plastic mouldings which comprises, incombination, a rotary element, an electric motor for intermittentlydriving the rotary element, a first series of relatively fixed camscarried by the r0- tary element, inlet and exhaust valves through whichthe pressure medium passes to and from the press, which are actuatedmechanically in a predetermined sequence by the first series of cams, asecond series of cams carried by-the rotary element which are co-relatedwith the said valve-actuating cams and movable simultaneously therewith,switch means actuated by the second series of cams including some foropening the motor circuit to bring the rotary element to rest atpredetermined positions in its cycle of movement, and one or moreswitches operated independently of the cams fo closing the motor circuitto re-start the rotary element in accordance with a cycle of pressoperations.

In order that the invention may be clearly understood and readilycarried into eifect, reference will now be made to the accompanyingdrawings which illustrate an embodiment of the invention by way ofexample as applied to the control means adapted, in addition tocontrolling the opening and closing of the dies, to permit a breathingoperation of the dies to take place after the initial closing togetherof the dies and also an inching movement of the dies when fully open ashereinafter explained. Referring to the drawings:

Figure 1 is a diagrammatic perspective view showing the control meansdisposed alongside a hydraulic moulding press,

Figure 2 is a side view of the control means with the adjacent side of acasing, in which the means is located, removed,

Figure 3 is a plan View of the control means with the roof of the casingremoved, 7

Figure 4 is an elevation of the control means looking in the directionof arrow A of Figure 2,

press P and the main control member comprises a disc 2 which is suitablysupported for rotation and driven intermittently by an electric motor 3through the intermediary of reduction gearing 4.

Fitted to this rotary disc 2, in predetermined spaced apart relation,are five cams or the equivalent lever lifting and lowering abutments 5,6, I, 8 and 9, three of which, i. e. 5, 6 and 'I are located on one sideof the disc 2 (and alone are visible in Figure 2) and coact with aroller or the equivalent anti-friction device It provided at the lowerend of an arm II secured to a hand lever IE or the like loaded by aspring I2a and controlling a valve I3 fitted in an inlet pipe I}!through which hydraulic medium passesto the press P so as to allowpressure to act on the movable d-ie I5. The remaining two cams 8 and 9are located on the other side of the disc 2 and co-act with a roller Iaat the lower end of arm 51? fitted to a hand lever or the like I6 loadedby a spring Ito and which controls a valve I! in an outlet or exhaustpipe'IB for the pressure medium. These cams 5 to 9 inclusive arereferred to herein as the first series of cams. A pipe I9, connected tothe hydraulic chamber of the press is common to both the inletand outletpipes I4 and I8, for delivering and exhausting the pressure medium.These five cams 5 to 9 are adjustably mounted respectively in a grooveor slot provided in each side of the disc 2 and are locked in positionby bolts 2I so that they can be preset to suit requirements fortreatment in producing difierent forms of mouldings from variousmaterials.

The side of the disc 2 having the pressure cams 5, 6 and I is fittedwith a second series of five cams or trip rollers 22, 23, 24, 25, andwhich may conveniently comprise rollers mounted on the outer ends ofrods 21 which are fitted at their inner ends to blocks adjustable in asecond and inner groove 28 in this latter side of the disc 2 and thesecams 22 to 25 co-act with three rockable switches 29, and 3I supportedadjacent the periphery of the disc 2 and this second series of cams 22to 26, which will-hereinafter be referred to as roller cams todistinguish them from the first series of pressure and exhaustvalve-operating cams 5 to 9, are co-related with the cams 5 to 9 inamanner described hereinafter. The, switches 29 and 30 control the supplyof current to the electric motor 3, and switch 3| controls a circuitenergising a time-switch 34 also for controlling the supply of currentto the motor 3. V

The circuit arrangement as seen in Figure 11 includes an electromagneticrelay 32a associated with the push-button 32, and a timing switch 34which is adapted to open its contacts 34a for a predetermined timeinterval on excitation of its winding 3%. The switches 20, 30 and 3| areshown in their normal positions in Figure 11, i. e. the positions theyassume when not acted upon by the cams 22 to 26. It willbe observed thatin these positions of the switches, the motor circuit is closed from thesupply terminal Z through the motor 3, switches 30 and 29, and normalclosed contacts 34a of timing switch 34 to the supply terminal n.

To enable a full cycle or operations to be described, it must here beexplained that at the end of a moulding operation, the movable die I5,at its extreme lowermost position, has moved downwardly over ejectorpins which act to push the moulding upwardly away from the die tofacilitate removal of the moulding by a hand strippen, Thus, whencommencing a new operation, ,a preliminary inching movement of the diehas a first to be efiected in an upward direction so as to clear the dieof the ejector pins before the die can be recharged with moulding powderand metal inserts (if the nature of the moulding includes same).

Figure 5 shows the positions of the members of the control mechanism'atthis stage with the exhaust cam 8 operative and the exhaust valve [1open, and with the pressure cams 5, 6 and 'I.

inoperative and the inlet valve I3 closed.

The movable die I5 is then inched or raised a short distance (see Figure6), so as to clear the ejector pins, by pressing the push button 32(Figures 1 and 11) mounted on the front wall of the casing I whichoperates the relay 32a. The relay 32a momentarily closes the circuit tothe electric motor 3 to drive the disc 2 sufficiently to allow theroller cam 22 (which acted on the switch 30 at the end of-the previouscycle of operations to break the motor circuit to the motor end stop thedisc) to move out of engagement with the change over switch 30 to allowthe switch to close the circuit to the motor 3' to render the latteroperative. During this movement of the disc 2 the exhaust cam 8 leavesthe arm I612 as in Figure 6 and permits the exhaust valve I! to close,and the pressure cam 5 then comes into action to open the inlet valve I3to effect slight upward movement'of the die I5.

The next step in the cycle of operations consists in stopping the diewhen it has cleared the ejector pins and the condition of the partsshown in Figure '7 is arrived at in which both the inlet and exhaustvalves l3 and H are closed so that the die remains stationary in itsslightly raised position. At this stage the exhaust cams moment theroller cam 26 engages with the switch 29 to open the entire circuit tothe motor which can then only be closed by way of a switch 43 actuatedby a guard which has to be moved into a protecting position before thepress can again be operated.

The die I5 is then charged with moulding pow der and inserts and theguard moved into position to screen the operator from the dies and thepush button 32' is again pressed to close the circuit to the electricmotor 3 momentarily to move the disc sufficiently to clear the rollercam 23 off the switch 30 whereupon the latter is rocked and closes thecircuit to the motor to drive the disc 2. With the continued movement ofthe disc the pressure cam 6 see (Figure 8) acts to open the inlet valvel3 and simultaneously the roller cam 24 moves into engagement with theswitch 30 to open the switch 30 and stop the motor. The inlet valve I3is now held open by'the cam 6 while pressure builds up to the desiredforce and the press is completely closed.

To ensure that the required pressure is built up to effect completeclosure of the press before the cycle continues, irrespective of thetime occupied between the positions of Figures '7 and 8, a switchingdevice 33 is provided for re-starting the motor and disc 2, this devicebeing adapted to operate only when the dies have actually come togetherwith full pressure. This switch 33 may be operated by the pressure ofthe fluid which operates the press (as illustrated in Figure 2) orinstead of the switch 33 being actuated by a predetermined pressure inthe fluid feed line, it may be mechanicall actuated by the movable presselement [5 when the same has reached its com plete closure position.

When required pressure has been built up, the switch 33 which, with theexhaust valve I! closed, is included in the pressure inlet system by apipe line 33a, becomes operative to close the motor circuit to cause thedisc 2 to run on to effect a breathing operation in which the exhaustcam 9 then opens the exhaust valve ll momentarily as shown in Figure 9and as the disc 2 in this instance is not stopped by any roller cam ofthe second series the breather cam 9 moves quickly out of engagementwith the exhaust lever arm 16b to close the exhaust I! and the momentarylowering of the die away from the fixed top die I5a enables breathing ofthe moulding to take place and allows gases to escape from between thedies which would otherwise blemish the moulding. As the breather cam 9moves out of engagement with the arm of the exhaust lever Ifib of themachine the remaining pressure cam I, engages the pressure lever arm ll(Figure 10) to cause the dies to close and at the same time the rollercam 25, associated with pressure cam 1 engages with the switch 3| andenergises a process timing switch 34 (Figures 13 and 11) on the machineand this timing switch 34, which is of any suitable design, opens theelectric motor circuit at its contacts 34a and causes the disc 2 tostop. The dies I 5 and l5a are now held closed, to enable the mouldingto be cured. This curing time is pre-set on the switch 34 and can bevaried according to the characteristics of the moulding but for thepurpose of general understanding of the invention can be said to beabout a minute. The breathing time effected by the rapid opening andclosing of the dies takes about one second.

At the end of the curing time, the timing switch 34 on the machineautomatically closes the circuit to the electric motor 3 (at itscontacts 34a) and the disc 2 again starts to rotate and the exhaust cam8 engages the arm IBa of the exhaust lever l6 and the hydraulic mediumis exhausted to allow the die l5 to travel downwards away from the upperdie 1501.. At this exhaust cam 8 engages the arm [6a of the exhaustlever [6, the roller cam 22 associated with the exhaust cam 8 actuatesthe switch and stops the motor 3 so that the exhaust cam 8 remains inengagement with the arm Ilia. of the exhaust lever IB to enable acomplete exhaust action to take place and the die to return to itslowest position as shown in Figure 5 in which ejector pins raise themoulding away from the bottom die.

The press is now open ready for the operator to remove the moulding andthis is effected by the operator raising the guard and inserting thehand stripper underneath the moulding, the operator thereafter againpushing the push button switch 32 on the press as already explainedwhich closes the circuit to the motor 3 (by means of the relay 32a) andthe pressure cam 5 again engages the arm H of the pressure lever [2 toallow the die 15 to rise about one inch to clear the ejector pins. Thepress then comes to rest ready for a subsequent operation, the rollercam 23 acting on the switch 30 and cutting out the motor 3 after thebottom die l5 of the press has risen the required distance andthepressure cam 5 has moved out of engagement with the lever.

The purpose of the relay 32a associated with the push-button switch 32is to maintain the circuit to the motor 3 closed a suificient time, sayfive seconds, so as to keep the motor '3 running and the disc 2 inaction to enable the roller cams 23 and 26 to clear the switch 30 andallow the latter to make contact and close the motor circuit again. I

The foregoing embodiment has only been described by way of example andvarious modifications are possible within the scope ofv the invention.For instance, the invention has been described with reference to theadaptation of an existing press and the pressureor exhaust cams can bemade to actuate means other than levers l2 and I6 associated with thepressure and exhaust valves l3 and I! of the press. Also, while it isconvenient and preferable to arrange both the pressure cams, exhaustcams and the roller cams on a single revolvingdisc 2 theselcams may beprovided respectively .onseparate discs if so desired. r

The relay 32a may if desired be dispensed with by constructing theswitch 32 so that it will remain closed for a predetermined period afterthe push-button has been pressed (say five seconds) and will thus holdthe motor circuit closed while the cam roller 23 or 25 is running offits associated switch.

What I claim is:

1. Control means for a hydraulic press for producing plastic mouldingscomprising, in combination, a rotary element, an electric motor forintermittently driving the rotary element, a, first series of relativelyfixed cams carried by the rotary element, inlet and exhaust valvesthrough which the pressure medium passes to and from the press, whichare actuated mechanically in a predetermined sequence by the firstseries of cams, a second series of cams carried by the rotary elementwhich are co-related with the said valve-actuating cams and movablesimultaneously therewith, switch means actuated by the second series ofcams including some for opening the motor circuit to bring the rotaryelement to rest at predetermined positions in its cycle of movement, andone or more switches operated independently of the cams for closing themotor circuit to re-start the rotary element in accordance with a cycleof press operations.

2. Control means according to claim 1, including an additional switch,also operated by a cam of the second series, for the purpose ofenergizing a, time switch for closing the motor circuit and restartingthe rotary element after a predetermined time interval following theclosure of the press at an appropriate point in the cycle of operations.

3. Control means for a hydraulic press for producing plastic mouldingscomprising in combination a rotary element, an electric motor forintermittently driving the rotaryelement, a first series of relativelyfixed camscarried by the rotary element, inlet and exhaust valvesthrough which the pressure medium passes to and from the press, whichare actuated mechanically in a predetermined sequence by the firstseries of cams, a second series of cams carried by the. rotary elementwhich are co-related with the said valve-actuating cams and movablesimultaneously therewith, switch means actuated bythe second series ofcams includingsome for opening'the motor circuit to bring the rotaryelement to rest at predetermined positions in its cycle of movement,afirst independent switch under control of the operator for the purposeof starting the motor to drive the rotary element until theswitch-operating cams of said rotary element are clear of the switchmeans controlled thereby, and a second independent switch comprising atime switch for keepingthe motor circuit open until a predetermined timeinterval elapses from the closing of the press through the first seriesof cams, said timing switch being set in operation automatically at aselected point in the cycle of operations so asvto cause a dwell in thecycle equivalent to-the said time interval substantially as described.

4. Control means according to claim 3, including a third independentlyoperated switch and means for automatically operating this third switchon closure of the press to close the motor circuit and recommencemovement of the rotary element for acontinuance of the cycle.

5. Control means for a hydraulic press for producing plastic mouldingscomprising, in combination, a rotatable disc, an electric motor forintermittently driving the rotatable disc, a first series of relativelyadjustable cams carried by the rotatable disc, means for locking saidcams in desired positions, inlet and exhaust valves through which thepressure medium passes to and from the press, which are actuatedmechanically in a, predetermined sequence by the first series of cams, asecond series of cams carried by the rotatable disc which are co-relatedwith the said valve-actuating cams and movable simultaneously therewith,switch means actuated by the second series of cams including some foropening the motor circuit to bring the rotary element to restat;predetermined positions in its cycle of movement, and one or moreswitches operated independently of the cams for closing the motorcircuit to re-start the rotary element in accordance with a cycle ofpress operations, and and a pressure switch in the hydraulic feed to thepress which is responsive to the pressure of hydraulic medium passing tothe press when the dies are first closed and which acts to close themotor circuit to commence a breathing operationonly after the desiredpressure has been built up.

6. Control means for a hydraulic, press for producing plastic mouldingscomprising, in combination, a rotatable disc, an electric motor forintermittently driving the rotatable disc, at first series of relativelyfixed cams carried by the rotatable disc, means for presetting andfixing said cams in required relative positions on said rotatable disc,inlet and exhaust valves controlling flow of pressure medium to and fromthe press, actuating levers connected with said valves and actuatedmechanically in a predetermined sequence by the first series of cams, asecond series of cams carried by the rotatable disc which are corelatedwith the said valve-actuating cams and movable simultaneously therewith,means for adjustably fixing said second series of cams to the rotatabledisc, the switch means actuated by the second series of cams includingsame for opening the motor circuit to bring the rotatable disc to restat predetermined positions in its cycle of movement, and one or moreswitches ope erated independentlyof the cams for closing the motorcircuit to restart the rotatable disc in accordance with a cycle ofpress operations.

RICHARD COLLIER.

REFERENQES CETED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,111,857 Jefiery Mar. 22, 19382,128,417 Kerr Aug. 30, 1938 2,375,252 Sayre May 8, 1945 2,454,362Whitmore et al Nov, 23, 1948

